Connector with magnetically controlled lock



Sept 7, 1954 J. H. SIMPSON CONNECTOR WITH MAGNETICLLY CONTRLLED .LOCK

Filed July 1o. 1953 2 Sheets-Sheet 1 Patented Sept. 7, 1954 CONNECTOR WITH MAGNETICALLY CONTROLLED LOCK James H. Simpson, Ladue, Mo., assignor to Joy Manufacturing Company, Pittsburgh, Pa., a corporation of Pennsylvania.

Application July 10, 1953, Serial No. 367,283

Claims.

This invention relates to electrical connectors of the plug-socket type such as may be used as cable connectors for electrically and mechanically connecting different lengths of cable to each other or by which such a length of cable may be connected to a stationary connector such as may be provided at the source oi power supply or on a machine.

This application is a continuation-in-part of applicants prior application Serial No. 126,389 filed November 9, 1949, now abandoned.

One of the objects of this invention is to provide an improved connector of this type which may be used safely in, but Without limitation thereto, gaseous mines, and in which improved means for preventing improvident separation of its parts is incorporated.

Another object is to provide such a connector in which the contacts are housed in an enclosure adapted to separate them from the ambient atmosphere at the time when any power circuit may be made or broken in the connector and in which improved means is incorporated for preventing any opening of the housing except a deliberate one by an authorized person.

A further object is to provide an improved locking means for the shell of a cable connector.

Still another object is to provide an improved locking arrangement which shall be tamper proof in the separated condition of the connector with which it is associated.

Still another object is to provide an improved locking arrangement for the sleeves of an enclosed-contact type of connection in which the sleeves are both normally locked against rotation about the enclosed contact-carrying bodies and in which either sleeve may be released for turning relative to such bodies and to the other tol make possible their disconnection.

A further object is to provide an improved arrangement for releasably locking a screw-collar type connector to a fixed-mounted receptacle.

An object is to provide an improved, explosionproof, locking coupling.

Yet a further object is to provide an improved connector having at least one rotatable coupling sleeve, in which connector suitably restricted and elongated flame paths are provided both at the threads of the coupling and at the mounting of the rotatable coupling.

Still another object is to provide an improved locking arrangement for the sleeves of an enclosed-contact type of connector in which variafacture without any necessity for alteration of the locking means employed.

Still a further object is to provide an improved locking means for a coupling of the threaded type in which the threads of the sleeves may be uninterrupted by any slots, grooves or the like.

Other objects will appear from the following description in which four illustrative embodiments and a modification of the invention will be described. It is to be understood, however, that the invention is susceptible of further modications within the scope of the appended claims, without departing from its principles or spirit.

In the accompanying drawings, in which the mentioned illustrative embodiments and the modification of the invention are shown:

Fig. l is a central longitudinal sectional view of a complementary pair of connectors embodying the invention, the connectors being shown nearly separated from each other, but held so that both complete separation and further movement of mutual approach are prevented without further relative rotation between the sleeves embodied in the connectors.

Fig. 2 is a transverse sectional view on the plane of the line 2-2 on Fig. 1.

Fig. 3 is a View generally similar to Fig. 1, but showing the parts of the connector fully drawn together.

Fig. 4 is a fragmentary view of a portion of the outside of the connectors at a point overlying the improved locking means.

Fig. 5 is a fragmentary view, looking inwardly at the outer periphery of one of the ball race sleeves, showing the lock in elevation.

Fig. 6 is a perspective View of the lock or latch element with associated spring.

Fig. 7 is a fragmentary section on the line '1 -1 of Fig. 3.

Fig. 8 is a fragmentary sectional view on the same plane as Fig. 1, showing the latch or lock drawn out into unlocking position.

Fig. 9 is a fragmentary View on the same plane as Fig. 2, showing the latch raised to inoperative position.

Fig. 10 is a central longitudinal sectional view of a complementary pair of connectors embodying the invention in a modified construction, the connectors in the same relative position as shown in Fig. l, each of the connectors equipped with a normally locked sleeve.

Fig. 11 is a central longitudinal sectional view of a fixed-mounted receptacle with a portable connector associated with it and releasably locked tions in sleeve length may be eiiected in manutoit.

Fig. 12 a similar central longitudinal sectional View of a modified construction of fixedmounted receptacle and portable connector.

Fig. 13 is a fragmentary sectional view showing a modied latch or lock element, being similar, as to the point where the section is taken, to Fig. 2.

'Since in most connectors of this type each member of a pair may be provided both with plug and socket contacts, although either member may be provided exclusively with one type of contact while the other member is provided eX- clusively with the other, and since the functioning will be generally the same regardless of the distribution between the members of the plug and socket contacts, the term plug-socket will be used hereinafter to designate a connector of either the uniform contact type or of the mixed contact type and without regard to whether it be a power plug-socket contact, a ground circuit plug-socket contact, or some other type. And the term -power plug-socket contacts will be used to designate those plug-socket contacts of the primary circuits, as distinguished, for eX- ample, from ground circuit plug-socket contacts.

In the rst embodiment, illustrated in Figs. 1 to 9 or" the accompanying drawing, the two connector elements l and 2 each have a body portion, the body portion of the connector element l being designated 31 and that of the connector element 2 being designated 32. These bodies may be formed of any suitable insulating material. Rubber is a suitable material, as is also neoprene; and the contacts are molded in the material of the bodies in a well-known manner.

Each of the connector elements, as illustrated, carries a plurality of contact elements forming portions of a power circuit, and each also carries contact elements forming portions of a ground circuit. Three pairs of power circiut contacts connecting three pairs of power conductors, one pair of ground contacts and one pair of ground conductors are used in the illustrative connector, but obviously this arrangement is but illustrative of many which may 'be employed. These power conductors and a ground conductor may be embodied in a single cable in a well-known manner. In Fig, 2 there may be seen three power plug contacts, 5p, 6p and 1p, and a pair of ground contacts 8p and Ss. to the power contact 5p and the ground contacts 5p and 8S, there are shown a power socket contact 5s; and power conductors 5l and 52 and ground conductors 31 and S2 are illustrated.

in this rst embodiment illustrated (and this is also true of the others), the ground circuit contacts 8p and 8S are so formed and so positioned with relation to the contacts for the power circuits that the ground circuit contacts engage each other before the power circuit contacts make contact with each other, and, upon separative movement of the parts oi the connector, the power contacts of each pair are mutually separated while the ground circuit is still maintained. lf, instead of a ground circuit, a pilot control circuit were employed for governing a switch mechanism for the power circuits, the relative lengths of the power circuit and additional (pilot) contact elements would be ordinarily selected so that the power circuits would not be broken until after opening of the control circuit and resultant deadening of the power circuits.

In order to insure that any spark or arc created by the opening or closing of the power circuits may not set up a ire or explosion hazard,

In Figs. l and 3, in addition an enclosure is provided for all of the contacts. The enclosure in the embodiment illustrated is provided by a pair of screw collars or sleeves II and I2 of non-magnetic material, one on each of the complementary connectors I and 2. The collar l! is arranged to be rotatable on the body I and is secured in place by a ball bearing comprising a row of balls I3 arranged to run in a groove ld in a non-magnetic metal collar i 5 providing a ball race for the bearing and molded into the connector body 31. The collar or sleeve i2 is molded integral with the connector body 32 and is thus non-rotatable, as is the case with the metal collar l5. The collar or sleeve member il has a relatively thicker portion i5 in which a groove El substantially wider than the diameter of the balls i3 is formed, the groove Il receiving the balls and, due to its width, permitting a certain amount of endwise movement of the collar or sleeve I I relative to the body 31. Other modes or assembling the collar I5 and the collar or sleeves I2 with the bodies 31 and 32 may, evidently, be employed. The nt between the sleeve II and the collar i5 is a close one and of substantial length, so that a flame proof relation is assured. The collar or sleeve tI has a generally cylindrical portion EI of larger internal diameter than the portion I 6, and has a counterbore 22, and. outwardly of the counterbore, an elongated threaded portion 23, the threads 24 upon which are adapted to cooperate with external threads 25 upon the outer portion of the collar or sleeve i2. A protector member 26 having a skirt portion 2l to extend over the threads 25 and protect the latter when the parts of the connector are separated from each other, is held in position on the collar or sleeve I2 by the resilient gripping' action of an internally grooved portion 29 thereof upon a collar portion 3G formed exteriorly on the collar or sleeve I 2. The protector member 2@ may be made of any suitable resilient material, as for example rubber or neoprene.

It will be evident that the connector elements I and 2 may be drawn together to establish the relation of the parts shown in Fig. 3, or may be separated, by separative movement beyond the relative position shown in Fig. l, by the turning of the collar or sleeve I I relative to the connector element I and to the connector element 2 when the connector elements I and 2 are in coaxial relation with each otherand are positioned for or with the proper interengagement of the power contact elements through the positioning action of the ground plug elements 8p and 3s. It will further be evident that the parts can neither be connected together nor separated from each other if rotation of the collar or sleeve l I relative to the connector element I, is prevented.

To prevent such relative rotation except when provision therefor is deliberately made, there is provided a magnetic locking or latchinT arrangement. rThis, in the first form illustrated, includes a circumferentially elongated, magnetic latch body 35, shown as laminated but capable of being formed from a single piece of metal, if desired. In the illustrative construction a plurality of la.L inae 3@ are stamped to shape and are held vtogether by one or more rivet elements 3l, the rivet element 37 herein being shown as securing to the latch structure a flexible spring element 38 having down-bent ears 3Q at either side of the bundle of laminae and having projecting resilient collapsible portions 4I! normally resiliently forcing the latch element 35 radially inwardly of a recess 4I formed in the portion I6 of the sleeve or collar I I. The latch element is shown as having a groove or seat 42 in its back surface to receive the spring element 38. The latch element 35 at its side toward the axis of the connector element I is formed with arcuate portions 43 and 44 between which there is an inwardly projecting portion 4,5 which is receivable in one or another of a series of elongated parallel-walled recesses or notches 46 formed in the periphery of the collar I5. `The recesses 46 have side walls 43 adapted relatively closely to fit the side walls 49 of the latch portion 45 when the latch is in radially inner position, thus to prevent material relative rotation in the inner position of the latch of the collar or sleeve I I relative to the collar I and the connector element I The recesses 45 are somewhat elongated in view of the range of free longitudinal movement of the collar or sleeve II, relative to the connector element I, provided by the widening of the ball receiving groove II.

A suitable magnet M, shown as a permanent horseshoe magnet, is adapted to have its opposite poles Pn and Ps applied to the periphery of the collar or sleeve II, and, in order to insure the proper positioning of the magnet M relative to the latch 35 so that the latter, which is of suitn able material for attraction by the magnet, shall be drawn outwardly by the magnet, a magnet guide 5G is suitably secured or mounted on the exterior of the collar or sleeve lI in a position overlying the recess 4I. It will be clear that if a magnet M of appropriate strength has its poles Pn and Ps brought to the surface of the sleeve or collar II in such a. position as is indicated in Figs. 8 and 9, the latch on the lock will be withdrawn, and then the collar or sleeve II may be rotated and the connector parts drawn together or separated as may be determined by their initial relative position and the direction of rotation of the sleeve or collar I I. The magnet will be made of such strength as to be held against the periphery of the sleeve or collar I I by its attraction to the latch element 35. Therefore it need not be manually held in position during coupling or uncoupling of the connector.

In Fig. 13 a somewhat different latch or lock arrangement is shown. In this gure the lock element 35' is made of a single piece of magnetic material, such as steel, and has its outer surface formed by a pair of intersecting surfaces 6I, 62 struck on relatively short radii and adapted to cooperate with cooperating mutually intersecting surfaces 53 and B4 bounding the locking element receiving recess 4I. The lock element 35' has a shallow groove 65 in its back, and spring means 66 is adapted to press the locking element inwardly and to cause engagement of its portion 45 in one or another of a series of notches or recesses 46 provided as in the first embodiment of the invention. Application of a suitable magnet to the periphery of the sleeve I I will release and hold in its withdrawn or unlatched position the locking element 35'.

From the foregoing description it will be clea-r that in the first embodiment of the invention illustrated the male threaded sleeve or coupling I2 is molded integral with the connector body 32 and so is non-rotatable, while the ball racemember I5 of the female, threaded coupling I I is likewise molded integral with and non-rotatable relative to its associated connector body 31. Locking is, then, accomplished by causing the female threaded sleeve or member I I to be non-rotatable except when unlocked by a magnet.

It will be evident that the lock or latch is completely enclosed between the threaded coupling member or sleeve II and the ball race member I5,

exit for gases from the chamber C.

and is accordingly tamper proof unless the right hand connector in Fig. 1 be dismantled. It will be evident that within the sleeves Il and I2, as the connectors are ,brought together, there will be enclosed a chamber C which will be out of communication with the ambient atmosphere when there is contact made between the power plug-socket contacts, and when these are disengaged from contact with each other. It will be evident that there is a restricted annular flame path, so to speak, between the sleeve portion I6 and the ball race member I5, and that this path is of substantial length longitudinally of the connector. Also, noting Fig. 1, it will be seen that theextent of thread engagement is such as to provide an elongated flame path at the only other It will be appreciated further that the length of the thread-supporting portions of the sleeves may be varied without necessity for modification of the lock structure and arrangement, so that regardless of thread lengths that might vary because of different contact sizes and lengths the locking arrangement may be made uniform. The lock desirably connects the sleeve to the ball race, thus connecting two metal parts firmly together through a metal latch or lock element.

If desired, the externally threaded sleeve I2 can be mounted on a ball race in the same manm ner as the sleeve I I, and have a similar, separate,

' magnetically releasable lock provided for it. Fig.

l0 shows such an arrangement, wherein either sleeve may be releasably rotatable, while the other is fixed to its connector body. In this gure, the sole diiference from what is disclosed in Fig. 1 will be found in connection with the connector element 2'. Even with respect to this connector element the difference from the disclosure of Fig. 1 is confined to but relatively few parts.

Instead of being molded integral 4with the connector body 32' the collar or 4sleeve I2 is supported similarly to the collar or sleeve Il on the connector I. In other words, a non-magnetic metal collar l5 is molded into the connector body. 32' and provides a ball race for a series of balls I3', and the collar or sleeve member I2 has a relatively thicker portion IG in which a groove Il substantially wider than the diameter of the balls i3 is formed, and the groove I7 receives the balls and, due to its widthpermits a certain amount of end-wise movement of the collar of sleeve I2 relative to the body 32'. As a result of this construction the collar or sleeve I2 is rotatably supported and also supported for longitudinal sliding movement with respect to the metal collar I5' and the connector 2. The iit between the sleeve I2 and the collar I5 is a close one and of vsubstantial length, so that a flame proof relation is assured.

Normally to prevent relative rotation between the collar or sleeve I2 and the connector body 32 and to permit relative rotation between these parts when desired, there is provided a locking or latching arrangement essentially the same as the one that is associated with the connector element I and there is illustrated a structure which is essentially the same as the latch 35 etc., and in view of the substantial identity of parts the same reference characters, but with primes, are used at the left hand side of Fig. 10. Essentially the only difference is that the latch releasing magnet is to be slid into position from left to right in Fig. l0 to release the latch 35, while it is slid to latch release position, to release the latch 35, in a right to left direction. Further de- 7 scription of this modification is not necessary, and it is simply to be noted that if it is more cons venient to hold the collar or sleeve Il against rotation while rotating collar or sleeve l2 lto effect connection or disconnection this is entirely possible. In other words which one of the collars or sleeves H, l2' is held against rotation with respect to its supporting body and which is rotated relative to its supporting body to effect disconnection of the connector is a matter of choice.

It is possible to utilize either of the separable halves illustrated in Fig. 10 with an appropriately constructed iixed receptacle; and in Fig. l1 there is disclosed a iixed-mounted receptacle with which a connector of the character illustrated in Fig. l at 2 is associated, while in Fig. 12 a xedmounted receptacle is shown associated with a connector of the type illustrated at l in Figs. 1, 3 and 10.

The fixed-mounted connectors in Figs. 1l and 12 are numbered I G! and l02 respectively. Each of these has a positioning collar, these numbered respectively C101 and C102. Each has a sleeve S non-rotatively mounted on it and held as by welding to a wall 464 (or lfl) the sleeves being respectively numbered S101 and S102. Otherwise the fixed-mounted connectors closely resemble as illustrated the releasable type connectors whose places they take. It will be evident that with these xed-mounted connectors there may be employed, in the case of the one numbered iol, a connector identical with the connector 2 of Fig. 10, and in the case o1" the fixed-mounted connector |02, a connector identical with the connector I, the magnetic latches associated with the releasable connectors being controlled as will be readily understood from the earlier portions `of 'this description to govern connection and detachment of the releasable connectors from the iXed-mounted-ones.

While there are in this application specifically shown and described four embodiments and a modication which the invention may assume in practice, it will be understood that these embodiments and modification are shown for purposes of illustration and that the invention may be further modified and embodied in various -other forms Without departing from its spirit or the scope of the appended claims.

What I claim is:

1. In a plug-socket connector, in combination, a pair of insulating bodies each carrying one or more power plug-socket contacts connectable with a power plug-socket contact on the other body, screw collars one on each of said bodies, one fixed against relative rotation with respect to its associated body and the other rotatably movable with respect to its associated body, said screw collars when screwed together and when unscrewed respectively effecting engagement and disengagement between the power plug-socket contacts on said bodies, and a magnetically releasable latch carried by the one of said collars which is rotatable relative to its associated body for holding it against rotation relative to the latter, said latch responsive to magnetic force applied at the exterior of, and exerted through, said one of said collars, and housed within, and protected from physical contact from outside, said plug-socket connector by said collar.

2. In a plug-socket connector, in combination, a pair of insulating bodies each carrying one or more power plug-socket contacts connectable with a power plug-socket Contact on the other body, housing means associated with. said bodies cooperating in providing a closed chamber within which separation of said power plug-socket contacts may be effected while out of communication with the ambient air, said housing means comprising collars interlockingly engageable by relative rotation and one on each of said bodies and themselves forming the circumferential boundaries of said closed chamber, one of said collars non-rotatively connected to its body and the other rotatably mounted on its body for turning relative to the latter, and means precluding inadvertent separative movement between said collars when said plug-socket contacts are engaged including a magnetically releasable latch carried by the one of said collars which is mounted for turning relative to its body, for connecting it releasably with the insulating body on which such collar is disposed, said latch responsive to magnetic force applied from without said collar and guarded by the latter from physical contact from the exterior of the connected plug-socket connector.

3. In a plug-socket connector, in combination, a pair of insulating bodies each carrying one or more power plug-socket contacts connectable with a power plug-socket Contact on the other body, housing means associated with said bodies cooperating in providing a closed chamber within which separation of said power plug-socket contacts may be eiected while out of communication with the ambient air, said housing means comprising screw collars one on each of said bodies, one of said screw collars non-rotatively connected to its body and the other rotatably mounted on its body, and means precluding inadvertent separative movement between said screw collars when said plug-socket contacts are engaged including a magnetically releasable latch carried by one of said collars and means forming a recess for receiving said latch mounted on the same body on which said last mentioned collar is and relative to which said collar is rotatable about its own axis, said last mentioned collar being of non-magnetic material and precluding physical access to said latch when said connector is in fully connected position but permitting magnetic force applied from the exterior of said collar to actuate said latch to released position.

4. In a plug-socket connector, in combination, a pair of insulating bodies each carrying one or more power plug-socket contacts connectable with a power plug-socket contact on the other body, screw collars one on each of said bodies, one fixed against relative rotation with respect to its associated body and the other having a bearing therefor upon its associated body, said bearing including a bearing ring upon said body, said screw collars when screwed together and when unscrewed eiecting opposite relative movements between the power plug-socket contacts on said bodies respectively effecting connection and separation between said contacts, and a magnetically releasable latch operable at will by the subjection thereof to a magnetic force carried by the one of said collars which is rotatable relative to its associated body and interengageable with the bearing ring on said body for holding said one of said collars against rotation relative to said ring and body.

5. In a plug-socket connector, in combination, a pair of insulating bodieseach carrying one or more power plug-socket contacts connectable with a power plug-socket contact on the other body, screw collars one on each of said bodies,

one iixed against relative rotation with respect to its associated body and the other rotatably and axially movable with respect to its associated body, said screw collars when screwed together and when unscrewed respectively effecting engagement and disengagement between the power plug-socket contacts on said bodies, and a latch, magnetically releasable at will, carried by, and housed within and covered exteriorly by the outer wall of, the one of said collars which is rotatable relative to its associated body for holding it against rotation relative to the latter.

6. In a plug-socket connector, in combination, a pair of insulating bodies each carrying one or more power plug-socket contacts connectable with a power plug-socket contact on the other body, screw collars one on each of said bodies, at least one of which is rotatable with respect to its associated body, said screw collars threadedly engageable and operative as their degree of threaded engagement is varied tc eiect relative axial movement, including actual separation, between the power plug-socket contacts on said bodies, and a magnetically releasable latch, releasable at will and enclosed within and normally connecting said at least one screw collar in nonrotative relation to its associated body.

7. In a plug-socket connector, in combination, a pair of insulating bodies each carrying one or more power plug-socket contacts connectable with a power plug-socket contact on the other body, mutually threadedly engageable screw collars of non-magnetic material, one on each of said bodies, and means precluding inadvertent separative movement between said screw collars including a releasable latch carried, and protected from extraneous contact, by one of said collars and lockingly engageable with the body on which said collar is, said latch responsive at all times to a magnetic force of appropriate magnitude applied from outside said collar.

8. In a plug-socket connection, in combination, a pair of insulating bodies each carrying at least one power plug-socket contact connectable with a power plug-socket Contact on the other body, non-magnetic means associated with said bodies cooperating to provide a closed chamber within which separation or engagement of said power plug-socket contacts may be eiected while out of communication with the ambient air, said housing means comprising screw collars threadedly engageable and disengageable respectively to eifect connection and disconnection between the power plug-socket contacts on said bodies, and means precluding relative movement between said screw collars to eiect engagement between said power plug-socket contacts including a magnetically releasable latch carried by, and accessible to magnetic force through, and housed within one of said collars for connecting said. collar in non-rotative relation to the insulating body which carries it.

9. As an article of manufacture, an insulating body carrying at least one plug-socket contact adapted for connection with another plug-socket contact towards and from which said insulating body is movable respectively to establish and to interrupt a connection, a non-magnetic screw collar rotatably supported on said body and cornprising a threaded portion and an unthreaded portion, said latter portion closely surrounding said body and having with the latter a close nt, and means for releasably holding said screw collar against rotation with respect to said body including a magnetically releasable latch carried by said l0 screw collar and subjectable to magnetic force through the latter and a recess in xed relation to said body with which recess the latch is engageable.

10. As an article of manufacture, an insulating body carrying at least one plug-socket contact adapted for connection with another plug-socket contact towards and from which said insulating body is movable respectively to establish and to interrupt a connection, a sleeve mounted on said body and iixed relative to the latter as regards both rotation and translation, a non-magnetic screw collar rotatably supported on said body and comprising a threaded portion and an unthreaded portion, said latter yportion surrounding said sleeve and rotatable relative to the latter, and means for releasably 'holding said screw collar against rotation with respect to said body including a magnetically releasable latch carried by the unthreaded portion of said screw collar and subjectable to magnetic force through the latter and a recess in said sleeve in which said latch is engageable.

1l. As an article of manufacture, an insulating body carrying at least one plug-socket Contact adapted for connection with another plug-socket contact towards and from which said insulating body is movable respectively to establish and interrupt a connection, a sleeve mounted on said body and fixed relative to the latter as regards both rotation and translation, a non-magnetic screw collar supported on said body for both rotation and translation relative to the latter and comprising adjacent one of its ends a threaded portion and adjacent the other of its ends an unthreaded portion, said latter portion surrounding said sleeve and rotatable relative to the latter and having between it and said sleeve means providing for limited relative reciprocation, and means for releasably holding said screw collar against rotation with respect to said body including a magnetically releasable latch carried by the unthreaded portion of said screw collar and subjectable to magnetic force through the latter and an elongated recess in said sleeve in which said latch is engageable in any of the longitudinally different positions of said collar relative to said sleeve.

12. As an article of manufacture, an insulating body carrying at least one plug-socket contact adapted for connection with another plug-socket contact towards and from which said insulating body is movable respectively to establish and to interrupt a connection between said plug-socket contacts, a non-magnetic screw collar rotatably supported on said body and having an unthreaded portion closely surrounding said body and having with the latter a close rotating iit, said screw collar further 4having a threaded portion for connection with a threaded portion on another screw collar surrounding an insulating body carrying a plug-socket Contact with which said at least one plug-socket contact is connectible, and means for holding said nonmagnetic screw collar against rotation with respect to said body with which it has a close rotating fit, including a magnetically releasable latch carried by said screw collar and subjectable to magnetic force through the latter and a recess in xed relation to said body with which recess the latch is engageable.

13. As an article of manufacture, an insulating body carrying at least one plug-socket contact adapted for connection with another plugsocket contact towards and from which said insulating body is movable respectively to establish and to interrupt a connection, a non-magnetic screw collar rotatably supported on said body and comprising a threaded portion and an unthreaded portion, said latter portion closely surrounding said body and having with the latter a close t, and both rotatable on and slidable longitudinally relative to said body, means for limiting the relative sliding movement between said screw collar and said body, and means for releasably holding said screw collar against rotation with respect to said body including a magnetically releasable latch carried by said screw collar and subjectable to magnetic force through the latter and a recess in xed relation to said body with which said recess the latch is engageable.

14. As an article of manufacture, an insulating body carrying at least one plug-socket contact adapted for connection with another plug-socket contact towards and from which said insulating body is movable respectively to establish and to interrupt a connection, a nonmagnetic screw collar rotatably supported on said body and comprising a threaded portion and an unthreaded portion, said latter portion closely surrounding said body and having with the latter a close it and both rotatable on and slidable longitudinally relative to said body, means for limiting the relaably holding said screw collar against rotation with respect to said body including a magnetically releasable latch carried by said screw collar and subjectable to magnetic force through the latter and an elongated recess on said body in which said latch is engageable in any of the longitudinally different positions of said collar relative to said sleeve.

15. In a coupling plug, in combination, connector elements of non-conducting material, power contact elements carried by said connector elements and mutually engageable to establish electrical circuit connections, non-magnetic coupling sleeves surrounding and freely rotatable relative to said connector elements, said sleeves releasably interlockingly connected to each other and housing and preventing separation of said contact elements and of said connector elements, lock means for preventing the release of one of said sleeves from the other, said lock means including a lock element housed within one of said sleeves and operable by pull exerted thereon by a magnet external to said sleeves to release said lock means, and means for guiding a magnet into position for the exertion of its pull on said lock element including a guide having opposite sides extending parallel to the axis of said sleeves for guiding the poles of a magnet and holding the latter against substantial movement circumfertive sliding movement between said screw collar entially 0f Said SleeVeS.

and said body including a ball bearing facilitating their relative rotation, and means for releas- No references cited. 

